Ultrasonography for investigating the effect of supplementing whole milk with plant-derived complex carbohydrates on curd clearance through the abomasum of dairy calves
Growth rates of dairy heifer calves and their performance at first lactation are enhanced by supplementing a whole milk diet with plant-derived complex carbohydrates and specific amino acids. At present it is unclear how such changes in nutrition from birth to weaning can affect a dairy cow’s subsequent lactations. The aim of this study was to establish the use of ultrasound to investigate if the transit time of milk is influenced by a supplement of plant-derived complex carbohydrates to whole milk. Initially, the use of ultrasonography for detecting curd after feeding whole milk in the abomasa of pre-ruminant dairy heifer calves (n=10) was determined. This was conducted using a sectorial probe (M-Turbo with C60x/5.2MHz transducer; Sonosite USA), at -10, 5, 30, 60 and 120 min after feeding. A score system was developed for fullness of the abomasum (0-3) and size of the curds (A-C). In trial 2, twenty two calves were individually fed whole milk (control group) until weaning (approximately 80 kg live weight); 4L whole milk per day (2L am and 2L pm) using an automated calf feeder. The remaining calves (supplemented group; n=21) were fed as per above, but whole milk was supplemented with a probiotic (X-Factor [XF], Bell-Booth Ltd, New Zealand) until 18 days of age and then XF was replaced with a source of plant-derived complex carbohydrates and selected amino acids (Queen of Calves [QoC], Bell-Booth Ltd) at a starting dose of 25g/L whole milk, increasing at day 20 of age to 37.5 g/L, and to 50g/L from day 21 of age until weaning. The groups were balanced for age, weight and breed. Ultrasonography of the abomasum was conducted as above. Supplementing whole milk with XF did not affect average retention time compared with calves fed whole milk. However, milk supplemented with QoC delayed the transit time of curd 1.4 ± 0.28 hours (32%) longer (P < 0.001) at four weeks of age and 0.7 ± 0.34 hours (14%) longer (P=0.05) at 8 weeks of age, compared with calves fed whole milk alone. These data indicate that milk supplemented with QoC slows transit time of curd in the abomasum, which may allow a greater absorption of nutrients to support early growth.
Keywords: curd, transit time, dairy heifer